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ORIGINAL ARTICLE Table of Contents  
Ahead of print publication
Correlation of platelet counts with coronavirus disease 2019 outcome in the second wave at a tertiary care center


 Department of General Medicine, ESIC-PGIMSR Model Hospital, Bengaluru, Karnataka, India

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Date of Submission05-Oct-2021
Date of Decision06-Nov-2021
Date of Acceptance20-Nov-2021
Date of Web Publication23-Feb-2022
 

  Abstract 


Background: A novel coronavirus, severe acute respiratory syndrome coronavirus 2, was first identified in December 2019 as the cause of a respiratory illness designated coronavirus disease 2019 (COVID-19). Laboratory parameters particularly the inflammatory markers such as D-dimer, C-reactive protein, ferritin, and others have been studied extensively and have been applied in categorizing the disease severity as well. However, studies regarding the role of platelet counts in the disease pathophysiology are limited. Aims: (1) To assess platelet counts in COVID-19 patients, (2) To correlate platelet counts with clinical outcome of COVID-19 patients. Materials and Methods: The present study was conducted on 200 patients admitted to ESIC MC and PGIMSR MODEL HOSPITAL, Bengaluru, during the study period from August 2020 to July 2021. Data were collected from case files of patients presenting to the Department of General Medicine Triage and COVID Ward/intensive care unit at ESIC Bangalore, fulfilling the inclusion criteria. Results: The mean platelet counts of the patients admitted with COVID-19 are 2.18 ± 1.32 × 105/mm3. Platelets among those who were discharged were 2.16 ± 1.09 × 105/mm3 and those among those who died was 1.71 ± 0.56 × 105/mm3. This difference was statistically significant with a P = 0.03. We also see that the lymphocyte counts are 14.03 ± 10.75% among those who were discharged and 10.13 ± 5.89% among those who succumbed to death. Conclusion: The present study concludes that COVID-19 patients with thrombocytopenia and lymphopenia are at increased risk of mortality. Hence, platelet count and lymphocyte count can be taken as prognostic indicators of COVID-19.

Keywords: Coronavirus disease 2019, lymphopenia, outcome, prognostic marker


How to cite this URL:
Rajanna AH, Ramanna B, Bellary VS. Correlation of platelet counts with coronavirus disease 2019 outcome in the second wave at a tertiary care center. APIK J Int Med [Epub ahead of print] [cited 2022 Sep 25]. Available from: https://www.ajim.in/preprintarticle.asp?id=338146





  Introduction Top


Coronavirus disease 2019 (COVID-19) is a major global public health and socioeconomic crisis, with over 220 million cases identified worldwide and more than 4.5 million deaths (as of September 2021).[1] The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has swept the globe in 2019 and 2020 causes COVID-19, a predominantly respiratory illness with 11.5%–13% mortality among hospitalized patients.[2],[3],[4] Eighty percentage of patients infected by SARS-CoV-2 may be asymptomatic or only mildly symptomatic, but around 10% develop severe respiratory symptoms that evolve to acute respiratory distress syndrome.[5] The appearance of disease clusters proved that human-to-human transmission is present.[6] Some researchers found that the full-length genome sequence of SARS-CoV-2 obtained from earlier patients had homology of 79.5% with the SARS-CoV sequence and homology of 96% with the whole genome of bat coronaviruses.[7] This provided valuable clues for examining the pathogenesis and clinical treatment of COVID-19.

Patients with COVID-19 pneumonia exhibit coagulation abnormalities, most commonly mild thrombocytopenia.[8] In this work, we study the platelet counts in COVID-19 patients and if it could be used as a marker of prognosis.

Aims and objectives

  1. To assess platelet counts in COVID-19 patients
  2. To correlate platelet counts with clinical outcome of COVID-19 patients.



  Materials and Methods Top


The present study was conducted in a hospital in Bengaluru, Karnataka, India. Ethical clearance for the study was obtained from the Institutional Ethics Committee (Reference No. 532/L/11/12/Ethics/ESICMC and PGIMSR/Estt. Vol. IV).

Data were collected from case files of patients presenting to the Department of General Medicine Triage and COVID Ward/intensive care unit (ICU) at ESIC Bangalore, fulfilling the inclusion criteria.

Inclusion criteria

Adult patients (18 years and above) with either reverse transcription–polymerase chain reaction (RT-PCR) or rapid antigen test positive for COVID-19 (moderate to severe).

(COVID-19:

Moderate – SpO2 90-94% at room air or Respiratory rate = 24–30 cycles per min [cpm].

Severe – SpO2 <90% at room air or respiratory rate ≥30 cpm).

Exclusion criteria

COVID-19: Mild cases, i.e., SpO2 >94% or respiratory rate <24 cpm.[9]

Data were collected from case files of patients admitted in the COVID Ward and ICU. History, laboratory investigations (total leukocyte counts [TLCs], N: L, D-dimer, ferritin, C-reactive protein (CRP), and lactate dehydrogenase [LDH]), and radiological investigations were collected. The patients were monitored, and the outcome was measured either as improved (clinical improvement, decreasing trend of inflammatory markers, and discharge) or deteriorated (clinically worsening, increasing trend of inflammatory markers, and death of the patient).

The patients were discharged according to the discharge policy of the Government of Karnataka after 10 days of onset of symptoms when the following criteria were met:

  1. No fever/symptoms for the last 3 consecutive days before discharge (without antipyretics)
  2. Maintains oxygen saturation >95% for the last 4 consecutive days (without oxygen support)
  3. Resolution of clinical signs/symptoms (based on the report of investigations)
  4. Resolution of breathlessness
  5. Repeat inflammatory markers (serum ferritin, LDH, D-dimer, and CRP) at the time of discharge should be in the normal range/decreasing trend.
  6. One RT-PCR/CBNAAT/true-NAT test shall be done after 3 days after complete clinical recovery and the patient has to be discharged if the report is negative. If the report is positive, the swab test shall be repeated after 72 h.[10]


Method of statistical analysis

Data were entered into Microsoft Excel datasheet and were analyzed using SPSS 22 version software. Categorical data were represented in the form of frequencies and proportions. The Chi-square test was used as test of significance for qualitative data. Continuous data were represented as mean and standard deviation. Pearson correlation was done to find the correlation between two quantitative variables and qualitative variables, respectively.


  Results and Analysis Top


As shown in [Table 1], the study included 200 patients with 9.05% of patients in 18–30 age group, 34.0% were the age group of 30–50 years, and 57% of patients were of >50 age group. Among the recruited patients, 117 (58.5%) were male and 83 (41.5%) of them were female.
Table 1: Descriptive statistics

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Out of 200 patients enrolled for the study, 170 were discharged and 30 succumbed to death. The age and gender distribution is shown in [Table 2].
Table 2: Demography

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Of 200, 40% of the COVID-19 patients who got discharged were hypertensive, 40.59% were diabetic, 7.65% had cardiac disorders such as ischemic heart disease, and 8.24% had thyroid disorders as their comorbidities, whereas 36.67% among the COVID-19 cases who died had hypertension, 33.33% had diabetes mellitus, 13.33% had cardiac disorders, and 6.67% had thyroid disorders. This was not statistically significant as shown in [Table 3].
Table 3: Comorbidities

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As we see in [Table 4], the mean platelet counts are 2.18±1.32 X105 cells/cu mm, the TLC 9.88±5.25 X 103 cells/cu mm.
Table 4: Laboratory parameters

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Here, in [Table 5], we see that the mean platelet count is 2.18±1.32 X 105/mm3. Platelets among those who were discharged was 2.16±1.09 X 105/mm3 and those among those who died was 1.71±0.56 X 105/mm3. This difference was statistically significant with a p value of 0.03. This suggests that the patients with Thrombocytopenia had increased risk of mortality.
Table 5: Comparison of laboratory parameters with the outcome of the patients: The below table has the variables checked for the significance level (P<0.05)

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Also, the neutrophils constituted of 76.83±16.01% of the TLC among those who got discharged and 84.66±7.65 aong those who expired with a p-value of 0.02 which was statistically significant. Lymphocytes constituted of 14.03±10.75% of the respective Total Leucocyte Counts (TLC) among those who were discharged and 10.13±5.89% among those who succumbed to death. This difference was also statistically significant with a p value of 0.04 thus implying that Neutrophilia and Lymphopenia in COVID-19 patients was associated with increased risk of mortality.

In [Table 6], we can see a negative correlation between NLR and Discharge of the patient i.e higher the NLR, lower was the discharge of the patients and mortality was thus higher.
Table 6: Correlation of laboratory parameters with outcome using Spearman's correlation the below is the correlation graph plotted using Excel (2103 (16.0.13901.20400))

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  Discussion Top


A meta-analysis of 7613 COVID-19 patients revealed that patients with severe disease had a lower platelet count than those with nonsevere disease. In addition, the nonsurvivors had a much lower platelet count than the survivors.[11],[12] A study conducted by Liu et al. from Wuhan concluded that thrombocytopenia at admission in COVID-19 patients was associated with a 4.24-fold increased risk of inpatient mortality.[2]

There are very few reports of the mechanisms of thrombocytopenia in patients with COVID-19, but thrombocytopenia is very common. Through analogy, three mechanisms of thrombocytopenia are hypothesized as per a study conducted by Xu et al.,[13] which state as follows:

  1. Direct infection of bone marrow cells by the virus and inhibition of platelet synthesis. Following virus infection, cytokine storm destroys bone marrow progenitor cells and leads to the decrease of platelet production. Lung injury indirectly results in the reduction of platelet synthesis
  2. Platelet destruction by the immune system
  3. Platelet aggregation in the lungs, resulting in microthrombi and platelet consumption.


Zhu et al. conducted a two-center observational study in March 2021 and inferred that thrombocytopenia was associated with deterioration of respiratory function and also the baseline platelet count was associated with subsequent and long-term mortality in critically ill COVID-19 patients.[14] Pranata et al., in January 2021, studied the role of platelets in COVID-19 and found out that thrombocytopenia was associated with higher mortality of the COVID-19 patients.[15]

In the present study, the outcome of the patients was measured in terms of either deterioration of patients' condition resulting in the demise of the patient or improvement in the patients' health resulting in the discharge of the patient, and their respective platelet counts were compared. One hundred and seventy patients were discharged in hemodynamically stable condition, whereas thirty of them expired. Platelet counts compared between them showed a significant difference with a P = 0.03. Hence, here, the low platelet counts point toward a poor outcome of the COVID-19 patients. However, continued controlled studies are necessary to guide the best treatment for COVID-19 patients and better elucidate the role that platelets play in COVID-19 pathophysiology.


  Conclusion Top


The present study concludes that COVID-19 patients with thrombocytopenia and lymphopenia are at increased risk of the severity of the disease and mortality. Hence, platelet count and lymphocyte count can be taken as prognostic indicators of COVID-19.

Limitation

The sample size was small and it is a single-center study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Dashboard WHO. WHO Coronavirus (COVID-19) Dashboard. World Health Organization. Available from: https://covid19.who.int/?gclid=Cj0KCQjw-NaJBhDsARIsAAja6dN0dnLD-oDtV268vExZ6QZ31E1wGbWI1Sd3Ie0_9hMnZ_mz-3miqp0aAsakEALw_wcB. [Last accessed on 2021 Sep 06].  Back to cited text no. 1
    
2.
Liu Y, Sun W, Guo Y, Chen L, Zhang L, Zhao S, et al. Association between platelet parameters and mortality in coronavirus disease 2019: Retrospective cohort study. Platelets 2020;31:490-6.  Back to cited text no. 2
    
3.
Tang N, Li D, Wang X, Sun Z. Abnormal coagulation parameters are associated with poor prognosis in patients with novel coronavirus pneumonia. J Thromb Haemost 2020;18:844-7.  Back to cited text no. 3
    
4.
Klok FA, Kruip MJ, van der Meer NJ, Arbous MS, Gommers DA, Kant KM, et al. Incidence of thrombotic complications in critically ill ICU patients with COVID-19. Thromb Res 2020;191:145-7.  Back to cited text no. 4
    
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Marietta M, Ageno W, Artoni A, De Candia E, Gresele P, Marchetti M, et al. COVID-19 and haemostasis: A position paper from Italian Society on Thrombosis and Haemostasis (SISET). Blood Transfus 2020;18:167-9.  Back to cited text no. 5
    
6.
The Lancet. Emerging understandings of 2019-nCoV. Lancet 2020;395:311.  Back to cited text no. 6
    
7.
Zhou P, Yang XL, Wang XG, Hu B, Zhang L, Zhang W, et al. A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature 2020;579:270-3.  Back to cited text no. 7
    
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Levi M, Thachil J, Iba T, Levy JH. Coagulation abnormalities and thrombosis in patients with COVID-19. Lancet Haematol 2020;7:e438-40.  Back to cited text no. 8
    
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Clinical Management of COVID-19. World Health Organization. World Health Organization; 2020. Available from: https://www.who.int/publications/i/item/clinical-management-of-covid-19. [Last accessed on 2021 Mar 05].  Back to cited text no. 9
    
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11.
Li Q, Cao Y, Chen L, Wu D, Yu J, Wang H, et al. Hematological features of persons with COVID-19. Leukemia 2020;34:2163-72.  Back to cited text no. 11
    
12.
Yang M, Ng MH, Li CK. Thrombocytopenia in patients with severe acute respiratory syndrome (review). Hematology 2005;10:101-5.  Back to cited text no. 12
    
13.
Xu P, Zhou Q, Xu J. Mechanism of thrombocytopenia in COVID-19 patients. Ann Hematol 2020;99:1205-8.  Back to cited text no. 13
    
14.
Zhu Y, Zhang J, Li Y, Liu F, Zhou Q, Peng Z. Association between thrombocytopenia and 180-day prognosis of COVID-19 patients in intensive care units: A two-center observational study. PLoS One 2021;16:e0248671.  Back to cited text no. 14
    
15.
Pranata R, Lim MA, Yonas E, Huang I, Nasution SA, Setiati S, et al. Thrombocytopenia as a prognostic marker in COVID-19 patients: Diagnostic test accuracy meta-analysis. Epidemiol Infect 2021;149:e40.  Back to cited text no. 15
    

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Correspondence Address:
Vaibhav S Bellary,
Plot No. 207, Sector 51, Saptagiri, BUDA, Laxmitek, Belgaum - 590 001, Karnataka
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ajim.ajim_106_21




 
 
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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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    -  Rajanna AH
    -  Ramanna B
    -  Bellary VS


Abstract
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